State-imposed mandatory quarantines for health workers returning to the U.S. from Ebola-sticken countries are having a “chilling effect” on humanitarian efforts in Western Africa, according to Doctors Without Borders, one of the major organizations that’s coordinating the effort to treat Ebola patients abroad.

In an email exchange with Reuters, the executive director of the aid group, Sophie Delaunay, said that health workers volunteering with Doctors Without Borders are already starting to change their travel plans due to concerns about how they’ll be treated when they return to the United States. Some of them are remaining in Europe for extra time to wait out Ebola’s 21-day incubation period to avoid “facing rising stigmatization at home and possible quarantine.”

“The risk of being quarantined for 21 days upon completion of their work has already prompted some people to reduce their length of time in the field,” Delaunay said in a statement, referring to her group by the acronym for the French version of its name, Médecins Sans Frontières. “Others will be less inclined to volunteer in the first place,” she said, noting that the group’s international volunteers all have full-time jobs as doctors, nurses, and other healthcare professionals in their home countries, and are using personal vacation time to make the trip to West Africa.

Delaunay said that non-American workers on the ground in West Africa have also started to fear that other countries may take cues from the U.S. and impose their own mandatory quarantines on people returning from MSF assignments. “There is rising anxiety and confusion among MSF staff members in the field over what they may face when they return home upon completion of their assignments in West Africa,” she told Reuters. “Some people are being discouraged by their families from returning to the field.”

“This will present significant operational disruptions at the field level for MSF and other organizations, and lead to an overall shortage of desperately needed health workers, precisely when the Ebola outbreak is as out of control as ever,” Delaunay warned.

The statement — which comes amid a legal standoff between one of its Ebola volunteers and the governor of Maine — offers the sharpest criticism yet on the government’s policies on Ebola aid workers, suggesting they are eroding MSF’s manpower and forcing American workers into temporary exile. The organization says the policies have also created a misperception that health care workers are endangering the public, even though a person who does not have symptoms cannot spread the virus. “[T]he risk of stigmatization of health workers is very real,” the group said in a statement. “It is imperative that the public maintains trust and confidence in all health workers.”

MSF policies have effectively mitigated risks for returning workers

Widespread fear and misinformation about the spread of Ebola has gripped many lawmakers in the U.S. These fears spilled over into full-fledged panic last week after Craig Spencer, an MSF doctor returning from West Africa, was diagnosed with the virus at a New York City hospital. Within days, New York and New Jersey introduced three-week quarantine policies that required anyone potentially exposed to Ebola to remain involuntarily confined, either in a hospital or at home, even if they posed no risk of transmitting the virus.

Doctors Without Borders physician Craig Spencer, who was recently diagnosed with Ebola in New York City.

MSF said the move was “not grounded on scientific evidence and could undermine efforts to curb the epidemic at its source,” adding that “medical science has demonstrated that asymptomatic people with Ebola infection do not transmit the virus. Ebola is also not an airborne virus, like cold or flu viruses. It is only transmitted through direct contact with an infected, symptomatic person’s body fluids, such as blood, vomit, and feces.” They further point out that “medical professionals specializing in [other] infectious diseases, such as tuberculosis and HIV/AIDS, do not face stigma and burdensome restrictions on their movements.”

MSF has an internal policy that requires workers not to return to their jobs for 21 days after finishing an assignment, and pays them wages to make up for that time. They also require employees to take their temperature twice daily, monitor for Ebola symptoms, stay within four hours of a hospital with isolation facilities, and immediately contact the MSF-USA office if any relevant symptoms develop.

These protocols, which are consistent with guidelines from the Centers for Disease Control and Prevention and the World Health Organization, guidelines, have been used for decades and, to date, have never led to a single secondary infection in the home country of an MSF worker. In fact, Dr. Spencer was the first international MSF field worker to ever report symptoms upon returning home. “The effectiveness [of MSF’s protocol] was apparent last week in New York, when MSF aid worker Dr. Craig Spencer immediately reported the onset of fever symptoms, setting into motion his secure transfer to Bellevue Hospital in Manhattan, where he is receiving comprehensive treatment,” the group said in a statement.

Quarantines treat health workers ‘like criminals and prisoners’

The fallout from the first two state-enforced quarantines has highlighted what health workers may encounter upon returning home. When nurse Kaci Hickox landed in New Jersey last Friday, she was detained by airport officials for hours and eventually forced into quarantine in an unheated tent next to a hospital. After three days, Gov. Chris Christie (R) allowed her to return to her home in Maine, where on Friday a judge rejected the state’s request to impose a mandatory isolation period.

Hickox, who has tested negative for Ebola twice and is not currently displaying any symptoms, is planning to sue the state of Maine for imposing a quarantine on her. “I truly believe this policy is not scientifically nor constitutionally just, and so I am not going to sit around and be bullied around by politicians and be forced to stay in my home when I am not a risk to the American public,” she told NBC this week. From the beginning of her high-profile disagreement with U.S. governors, Hickox has expressed concern about how this policy will affect her colleagues in the field working to battle the virus at its source.

“I sat alone in the isolation tent and thought of many colleagues who will return home to America and face the same ordeal. Will they be made to feel like criminals and prisoners?” the nurse wrote in an essay published on the Dallas Morning News about her quarantine in New Jersey. “We need more health care workers to help fight the epidemic in West Africa. The U.S. must treat returning health care workers with dignity and humanity.”

‘Unfair and unwise’ policies

In addition to Doctors Without Borders, other leading medical authorities have come out against state-imposed quarantines for returning aid workers. One of the most prestigious peer-reviewed medical journals in the world, the New England Journal of Medicine, called the policy “unfair and unwise” in a recent editorial. Dr. Anthony Fauci, a top official at the National Institutes of Health, has said that isolating health workers who aren’t displaying any symptoms is “draconian.” The Association for Professionals in Infection Control and Epidemiology, the leading group for doctors working to combat contagious diseases, has emphasized that these quarantines are totally unnecessary because Ebola is not contagious when people are not displaying symptoms.

“There are other ways to adequately address both public anxiety and health imperatives, and the response to Ebola must not be guided primarily by panic in countries not overly affected by the epidemic,” Delaunay said in a recent statement. “Any regulation not based on scientific medical grounds, which would isolate healthy aid workers, will very likely serve as a disincentive to others to combat the epidemic at its source, in West Africa.”

The Centers for Disease Control and Prevention laid out new guidelines Monday calling for voluntary isolation and monitoring of travelers exposed to Ebola, while rejecting the idea of placing asymptomatic people under mandatory quarantines. The updated advice to state and local officials breaks down travelers’ risk level into categories: high risk, some risk, low risk and no risk (see the figure at left for an overview of the guidelines). Those at highest risk are anyone who’s had direct exposure to an Ebola patient’s body fluids, including health care workers who suffer a needle-stick injury during a patient’s care. Health workers who cared for Ebola patients while wearing proper protective equipment would be considered at “some risk.”

The CDC recommends that people in the highest risk category isolate themselves from others for 21 day, while those at “some risk” are advised to engage in “direct active monitoring” (including daily temperature readings and regular contact with local health authorities) and, in some cases, to stay away from public transportation and crowded public places–maintaining a distance of 3 feet from others–and restrict travels.

‘We may lose the services of many good people’

MSF’s statement is just the latest example showing how fears over Ebola are affecting the medical community’s ability to conduct its work. On Thursday, Louisiana health officials announced that any health workers who have been in Sierra Leone, Liberia, or Guinea in the past three weeks will not be allowed to travel to New Orleans to attend a major conference on infectious diseases, a category that includes Ebola. The American Society of Tropical Medicine and Hygiene has agreed to abide by that order, but released a statement this week noting that the group “does not agree with the policy.”

“The ASTMH Annual Meeting serves a much larger good, bringing scientists and dedicated professionals together from around the world to further the scientific discourse and ultimately improve the health of those suffering from disease,” the group writes. “We deeply regret that some of our attendees are affected by Louisiana’s travel advisory.”

Armand Sprecher, an MSF doctor based in Brussels, also spoke out this week about what he called the media’s overreaction to the disease, which has “sent a chill” through its volunteer force: “Dr. Craig Spencer is having a hard enough time fighting the disease, but it’s only been made worse for him and his family by the criticism and outrage that was heaped upon him by the press,” he wrote in an op-ed in The New Republic, which was highly critical of the magazine’s own reporting. “If they are discouraged by the prospect of three weeks of near total isolation on their return, we may lose the services of many good people,” Sprecher warned.

West Africa is already facing a critical shortage of health workers; the WHO estimates that an additional 5,000 trained healthcare personnel are needed in the region. Without the help of more international health workers like Dr. Spencer and Hickox, the Ebola epidemic will take longer to control; more West Africans will die; and the U.S. will be no safer in the end. The country will remain susceptible to imported cases and to small clusters of cases — as already happened in Dallas — until the outbreak is brought under control at its epicenter.

“The best way to protect Americans from Ebola is to stop the outbreak at its source,” President Obama said last week at ceremony honoring doctors and nurses who have been or are going to West Africa. “If we are not dealing with this problem there, it will come here.”